Typically, short-range communication links between a transmitting unit and a receiving unit are established through wires. For example, a mouse or a keyboard may be connected to a computer and a video game controller may be connected to a video game console by a pair of wires or a coaxial cable. Restrictions in the length of a cable connecting the transmitting unit to the receiving unit may confine the location of either the transmitting unit or the receiving unit. In particular, the length of the cable connecting the video game controller to the console may prevent a user from sitting at a desired location such as a couch. Additional extension cables may be required to connect the video game controller to the console to establish a communication link. However, the additional extension cables may become entangled, which further restrict the location of the controller and enhance the frustration of the user for having to untie the cables. Furthermore, during periods of "excitement" when a video game is in play, the cables that connect the console and the controller may be loosened by the user's movement of the controller. Accordingly, the communication link established between the controller and the console may be disconnected. Such a catastrophic event during a critical and intense moment in a game may cause distress to the user.
More and more communication links are generated through wireless technology. Infrared waves, for example, have been used for generating wireless communication links between a transmitting unit and a receiving unit. In particular, the remote controllers for televisions, stereos, compact disc players, video cassette recorders, digital video disc players or any other entertainment equipment may use infrared waves. The utility of infrared waves, however, suffer many restrictions such as line-of-sight and directionality. In the context of operating a video game, for example, a wireless controller may use infrared waves to communicate with a video game console. An object, however, may impede a user's line-of-sight in which a signal may not be sent to the video game console by the controller. For example, a person or a piece of furniture may obstruct the line-of-sight path between the controller and the console. During the periods of "excitement" in a video game, the user rarely considers maintaining the controller within the line-of-sight path of the console. Furthermore, directionality may require the user to aim the controller within a particular range of angles with respect to the console to generate the communication link. A user sitting perpendicularly to the console may not have the controller correctly aimed at the console. That is, the controller may be aimed straight ahead, and then a communication link may not be established between the controller and the console.
Radio frequency may be used to generate short-range communication links. Current short-range radio frequency systems utilize conventional radio communication techniques of synthesizer and heterodyning to support communications in frequency bands such as the 2.4 Gigahertz (GHz) Industrial, Scientific, and Medical (ISM) band. The main components of a 2.4 GHz heterodyne receiver generally include: (1) a radio frequency (RF) amplifier, which is tuned to the desired radio frequency; (2) a first local oscillator; (3) a first mixer for heterodyning to a first intermediate frequency; (4) a first intermediate frequency (IF) amplifier; (5) a second local oscillator; (6) a second mixer for heterodyning to a second intermediate frequency; (7) a second IF amplifier; and (8) a demodulator. To prevent images and other spurious responses, the RF amplifier typically provides frequency selectivity to attenuate the mixing image. The first IF amplifier typically comprises ceramic or surface acoustic wave (SAW) technology filters to prevent spurious responses. Both local oscillators typically include synthesizers. However, such synthesizers and heterodyne techniques are neither low-power nor cost-effective to generate short-range wireless data communication links. Therefore, a need exists for a method and an apparatus for generating short-range wireless communication links through an over-the-air channel on a predetermined RF carrier at low-power and low-cost.